Improving Physicochemical Properties of Catfish Gelatin Films through the Maillard Reaction Assisted by Radio Frequency

Abstract

Encapsulation is a promising technology in food industries and biotechnology field. Native gelatin extracted from the catfish skins to be made as the wall materials of encapsulation have potential applications. High qualities of the wall materials are mainly dependent on the low permeability, high thermostability, and good mechanical properties. In this study, lactose was applied to have the Maillard reaction (MR) with 3.33% gelatin solution, finally, the Maillard reaction products (MRPs) were formed to change the physicochemical properties of gelatin biofilm. Additionally, radio frequency (RF) system instead of the water bath (WB) method was used to heat MR because of its volumetric heat transfer, huge heat energy, deep heat penetration, and homogeneous heating mode. The viscosity, pH value, and the absorbance (294nm & 420nm) were important solution indicators to measure to extent of MR. Meanwhile, water vapor permeability (WVP), oxygen transmission rate (ORT) and mechanical properties were crucial factors to the gelatin films. Other film properties, such as light transmission (LT) and glass transition temperature (Tg) were also evaluated. Among the different reactant ratio (1:2, 1:1, 2:1) and heating time (2 h, 4 h, 6 h) used, the 1:1 MR system treated by RF heating at 2 h obtained the optimal yield of the MRPs, subsequently rendered the preferred tensile strength (TS), elongation (E), Tg and OTR, while increased WVP. Furthermore, MR treated by RF heating could greatly reduce the heating time and save the energy consumption.